Risk factors associated with methylisothiazolinone contact sensitization

The preservative methylisothiazolinone (MI) has become an important allergen, with a dramatic increase in sensitization prevalence being seen over the last few years.

To examine risk factors associated with MI sensitization, in order to identify targets of prevention aimed at curtailing the present epidemic.

On the basis of contact allergy surveillance data collected by the Information Network of Departments of Dermatology (www.ivkd.org), 2009-2012, in the course of 28,922 patch tests with MI, 500 ppm in water, included in a series of cosmetic preservatives, logistic regression analysis was employed to quantify the risk associated with a number of putative risk factors.

The prevalence of MI sensitization increased from 1.94% in 2009 to 6.02% in 2012, the increase being mainly driven by female patients aged≥ 40 years, patients with face dermatitis, and the use of cosmetics. Adjusted multifactorial analysis additionally identified several occupations (e.g. painters and beauticians) and ano-genital dermatitis as risk factors for MI sensitization.

The present use concentrations of MI, both cosmetic and industrial, are too high; (self-)regulatory action is urgently needed. MI should be added to the baseline series.